page 21-22 OmniSwitch AOS Release 7 Network Configuration Guide March 2011
command to select the type of TCM. See “Configuring Tri-Color Marking” on page 21-22 for more infor-
mation.
Based on the TCM type used, packets are marked as follows:
Configuring Tri-Color Marking
Tri-Color Marking (TCM) is a supported technique for policing traffic. See “Tri-Color Marking” on
page 21-21 for an overview of how this implementation of TCM works.
Configuring TCM is done by creating a TCM policy action using the following QoS policy action
command parameters:
• cir (Committed Information Rate, in bits per second)
• cbs (Committed Burst Size, in bytes)
• pir (Peak Information Rate, in bits per second)
• pbs (Peak Burst Size, in bytes)
• color-only (mark packet color only)
Consider the following when configuring TCM policy actions:
• There is no explicit CLI command to specify the mode in which the TCM meter operates. This mode is
determined by whether or not the PIR is configured for the policy action and if the value of the PIR is
greater than the value of the specified CIR. In this case, the trTCM mode is triggered; otherwise, the
srTCM mode is used.
• This implementation of TCM is in addition to the basic rate limiting capabilities provided through the
maximum bandwidth and maximum depth parameters used in QoS policy actions and the ingress and
egress bandwidth parameters used in VLAN Stacking Service Access Point (SAP) profiles. When these
parameters are used, the TCM meter operates in the Single-Rate TCM mode by default.
• A srTCM policy action specifies both a CBS and PBS value. Default values for these burst sizes are
used if one is not specified using the optional cbs and pbs parameters.
TCM Type Meter Compliance Marker Color Result
Single-Rate
(srTCM)
Packet is CIR/CBS compliant. GREEN Packet is transmitted with the Drop
Precedence set to LOW.
Packet is not CIR/CBS compli-
ant but is CIR/PBS compliant.
YELLOW Packet is transmitted with the Drop
Precedence set to HIGH (packet is
dropped first when congestion
occurs on the egress queue.
Packet is neither CIR/CBS nor
CIR/PBS compliant.
RED Packet is dropped at the ingress.
Two-Rate
(trTCM)
Packet is CIR/CBS compliant. GREEN Packet is transmitted with the Drop
Precedence set to LOW.
Packet is not CIR/CBS compli-
ant but is PIR/PBS compliant.
YELLOW Packet is transmitted with the Drop
Precedence set to HIGH (packet is
dropped first when congestion
occurs on the egress queue.
Packet is neither CIR/CBS nor
PIR/PBS compliant.
RED Packet is dropped at the ingress.
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